Lipoprotein adsorbent and lipoprotein adsorber made with the use of the same

ABSTRACT

The present invention has its objects to provide an adsorbent capable of efficiently adsorbing and removing LDL and VLDL from various lipoprotein-containing solutions, as well as a lipoprotein adsorber in which the adsorbent is used. This invention is related to a lipoprotein adsorbent which comprises a water-insoluble carrier having, on at least one part of the surface of the carrier, at least one group (other than p-nitrobenzoic acid) selected from the group consisting of groups represented by the general formula, and groups represented by the general formula.

TECHNICAL FIELD

The present invention relates to a lipoprotein adsorbent. Moreparticularly, it relates to a lipoprotein adsorbent for selectivelyadsorbing and removing lipoproteins, including apoB proteins, inparticular low density lipoproteins (hereinafter, LDL) and very lowdensity lipoproteins (hereinafter, VLDL), from blood constituents or thelike.

BACKGROUND ART

Lipoproteins occurring in blood, in particular LDL and VLDL, commonlyknown as a villain cholesterol, contain a large amount of cholesteroland are known to be causative of atherosclerosis. On the other hand, thehigh density lipoprotein (hereinafter, HDL), commonly known as a goodycholesterol, is known to serve as an atherosclerosis retarding factor.Therefore, means is desired by which LDL and VLDL can be removed fromblood constituents or the like without removing HDL therefrom.

As the methods currently in clinical use for removing LDL and VLDL,there can be mentioned plasma exchange therapy, double filtrationmembrane method, use of adsorbents (immobilized dextran sulfate,immobilized anti-apoB antibody, etc.) and HELP system, among others.

However, the membrane method brings about simultaneous removal of aconsiderable amount of HDL together with LDL and VLDL and thereforefails to satisfy the selectivity for lipoprotein. Further, there is adrawback that plasma proteins are partly removed simultaneously, hencesuch losses need to be repaired by supplementation.

As the removing method using an adsorbent, there can be mentioned, forexample, the removing method using the so-called immunoadsorbentcomprising an antibody or the like immobilized and the removing methodusing an adsorbent comprising a compound having affinity for LDL andVLDL (hereinafter, ligand) as immobilized according to the principle ofthe so-called affinity chromatography.

The removing method using an immunoadsorbent, however, has problemsalthough it satisfies the selectivity for lipoprotein; thus, forexample, the antibody to be used is not readily available or is poor ineconomy or storage stability or is difficult to sterilize.

In the removing method which uses an adsorbent based on the principle ofaffinity chromatography, heparin, dextran sulfate and the like are usedas ligands of adsorbents. The adsorbents in which these ligands are usedshow good selectivity for lipoprotein and the ligands themselves are notvery expensive. In cases where a ligand is used in large amounts,however, it is desired that said ligand is less expensive.

As an adsorbent for adsorbing and removing lipoproteins by using such anorganic compound as phenyl glycidyl ether as a ligand and utilizing thehydrophobic interaction between the phenyl group and the hydrophobicsites of the lipoprotein surface, there is commercially available PhenylSepharose CL-4B (product of Pharmacia Fine Chemicals). However, thisadsorbent, though it is inexpensive, adsorbs large amounts of HDL aswell as LDL and VLDL and thus has a serious drawback from the standpointof the selectivity for lipoprotein.

DISCLOSURE OF THE INVENTION

In view of the above-mentioned state of the art, the present inventionhas its objects to provide an adsorbent capable of efficiently adsorbingand removing LDL and VLDL from various lipoprotein-containing solutions,such as blood, serum, plasma, dilutions thereof, and solutions resultingfrom pretreatment of them for removal of blood corpuscles or serumprotein or the like as well as a lipoprotein adsorber in which saidadsorbent is used.

Japanese Kokai Publication Sho-62-186940 describes a lipoproteinadsorbent which comprises a water-insoluble carrier having aniline or ananiline derivative immobilized thereon and, in Japanese KokaiPublication Sho-63-208764, there is described a lipoprotein adsorbentcomprising a water-insoluble matrix and, on the surface thereof, a grouprepresented by the general formula —NR^(a)R^(b) in which R^(b) is agroup such that the corresponding compound R^(b)H has a logarithmicvalue (log P) of 0 to 3.2, P being the partition coefficient in thewater-octanol system, and it is disclosed that an inexpensivelipoprotein removing apparatus capable of removing LDL and VLDLselectively can be provided by using said adsorbent.

Referring to these technologies, the present inventors made furtherinvestigations and, as a result, found that when the lipoproteinadsorbents having a group represented by the above general formula—NR^(a)R^(b) further have a substituent in the meta position of R^(b),which is the aromatic ring-containing atomic group in said group—NR^(a)R^(b), the selectivity for LDL and VLDL, in particular, is high,that when, in cases where R^(b) is a group bound to an aromatic ring viaan atom or atomic group, it is bound to the aromatic ring via a carbonylgroup, the selectivity for LDL and VLDL is high; and that when R^(b) hasa specific functional group, the selectivity for LDL and VLDL isparticularly high.

Thus, the present invention provides a lipoprotein adsorbent comprisinga water-insoluble carrier having, on at least one part of the surface ofsaid carrier, at least one group (other than p-nitrobenzoic acid)selected from the group consisting of groups represented by the generalformula

(hereinafter also represented as “—NR¹φ¹X”) (wherein R¹ represents ahydrogen atom or a methyl or ethyl group, φ¹ represents an atomic groupcomprising an aromatic ring bound directly or via one atom to thenitrogen atom, X represents a substituent atom or atomic group bound toa meta position of said aromatic ring, and φ¹X represents an atomicgroup such that the compound represented by Hφ¹X has a logP value (Pbeing the partition coefficient in the water-octanol system) of 0 to3.2), and groups represented by the general formula

(hereinafter also represented as “—NR²COφ²Y”) wherein R² represents ahydrogen atom or a methyl or ethyl group, CO represents a carbonylgroup, φ² represents an atomic group comprising an aromatic ring boundto the nitrogen atom via said carbonyl group, Y represents an atomicgroup bound to said aromatic ring, to the exclusion of the case whereHφ²Y is benzene, and COφ²Y represents an atomic group such that thecompound represented by Yφ²COH has a logP value of 0 to 3.2 (P being thepartition coefficient in the water-octanol system). The presentinvention further provides a lipoprotein adsorber which comprises anadsorption section containing the lipoprotein adsorbent mentioned above,a liquid inlet section for a liquid to flow into said adsorption sectionand a liquid discharge section for the liquid that has flown into saidadsorption section to flow out of said adsorption section.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the present invention is described in detail.

The lipoprotein adsorbent of the present invention has, on at least onepart of the surface of a water-insoluble carrier, at least one groupselected from the group consisting of a group represented by the generalformula —NR¹φ¹X (wherein R¹, φ¹ and X are as defined above) and a grouprepresented by the general formula —NR²COφ²Y (wherein R², CO, φ² and Yare as defined above).

In the above group —NR¹φ¹X, R¹ represents a hydrogen atom, methyl groupor ethyl group. The above-mentioned φ¹ represents an atomic groupcomprising an aromatic ring bound to the nitrogen atom either directlyor via an atom. The above-mentioned X represents an atomic group boundto the meta position of said aromatic ring. Further, φ¹X resulting frombinding φ¹ and X to each other is such that the compound represented byHφ¹X has a logP value of 0 to 3.2 (P being the partition coefficient inthe water-octanol system).

The logP value, which is the logarithmic value of the partitioncoefficient in the water-octanol system, is a parameter indicative ofthe degree of hydrophobicity of a compound. A typical method ofdetermining the partition coefficient P is as follows.

The compound is dissolved in octanol (or water), an equal volume ofwater (or octanol) is added to the solution, and the mixture is shakenon a Griffin flask shaker (product of Griffin and George Limited) for 30minutes and centrifuged at 2,000 rpm for 1 to 2 hours. Theconcentrations of the compound in the octanol layer and aqueous layerare determined by any of various methods, for example byspectrophotometry or GLC (gas-liquid chromatography), and the P value iscalculated as follows:

P=Coct/Cw  (1)

where Coct is the concentration of the compound in the octanol layer andCw is the concentration of the compound in the aqueous layer.

In accordance with the present invention, the logP value for thecompound represented by Hφ¹X is 0 to 3.2. If the logP value is less than0, the hydrophobic interaction with lipoproteins will be weak, hence theadsorbing ability for lipoprotein will be poor. If said logP valueexceeds 3.2, not only LDL and VLDL but also HDL and other proteins aresimultaneously adsorbed, hence a problem from the selectivity viewpointwill arise. The above range is thus critical. It is preferred that saidlogP value be 0.8 to 2.7. While it is stated in Japanese KokaiPublication Sho-63-208764 that the hydrophobicity of φ¹X in the group—NR¹φ¹X mentioned above plays an important role in the adsorption oflipoproteins, it has now newly been found in the present invention that,in addition to the degree of hydrophobicity, the position of thefunctional group bound to the aromatic ring is related to theadsorptivity for lipoproteins and that when the adsorbent has thefunctional group in the meta position, it shows particularly highselectivity as compared with those having the functional group in theortho or para position.

Said logP value may vary to some extent but not to a great extentdepending on the position (ortho, meta, para) of the substituentfunctional group on the aromatic ring, so that said logP value may bethe same as in the case of Japanese Kokai Publication Sho-63-208765.

The term “selective” in this specification means that the adsorptivityof HDL for the adosorbent is low and the adsorptivity for LDL and VLDLis high. The value calculated according to the following formula (2) isused as an index of selectivity.

Index of selectivity=(% adsorption of HDL)/(% adsorption of LDL)  (2)

The nearer to zero the value of the above formula (2) is, the higher theselectivity is.

The aromatic ring contained in the above-mentioned group φ¹ is notparticularly restricted but includes, among others, benzene, pyridine,pyrimidine and triazine rings and condensed rings derived from these.

The above-mentioned compound represented by Hφ¹X is not particularlyrestricted but may be any compound having a logP value of 0 to 3.2.Thus, for example, when the aromatic ring contained therein is a benzenering, there may be mentioned toluene, m-xylene, ethylbenzene, phenol,benzyl alcohol, 2-phenylethanol, benzaldehyde, anisole, phenetole,phenylacetic acid, phenoxyacetic acid, methyl benzoate, nitrobenzene,chlorobenzene, bromobenzene, fluorobenzene, m-dinitrobenzene,3-nitrobenzaldehyde, 3-nitroanisole, 3-nitrotoluene, benzamide,acetophenone, 3-ethylphenol, 3-ethoxyphenol, acetanilide, 3-methylbenzylalcohol and the like.

When the aromatic ring contained in said φ¹is a pyridine ring, as saidHφ¹X, there can be mentioned, for example, 2-amino-4-fluoropyridine,2-amino-6-fluoropyridine, 3-amino-5-fluoropyridine,4-amino-6-fluoropyridine, 2-amino-4-nitropyridine,2-amino-6-nitropyridine, 3-amino-5-4-nitropyridine,4-amino-6-nitropyridine, 2-amino-4-hydroxypyridine,2-amino-6-hydroxypyridine, 3-amino-5-hydroxypyridine,4-amino-6-hydroxypyridine, 2-amino-4,6-difluoropyridine,2-amino-4,6-dinitropyridine, 2-amino-4,6-dihydroxypyridine,4-amino-2,6-difluoropyridine, 4-amino-2,6-dinitropyridine,4-amino-2,6-dihydroxypyridine, 4-fluoropyridine-2-carboxamide,6-fluoropyridine-2-carboxamide, 4-nitropyridine-2-carboxamide,6-nitropyridine-2-carboxamide, 4-hydroxypyridine-2-carboxamide,6-hydroxypyridine-2-carboxamide, 2-carboxy-4-fluoropyridine,2-carboxy-6-fluoropyridine, 2-carboxy-4-nitropyridine,2-carboxy-6-nitropyridine, 2-carboxy-4-hydroxypyridine,2-carboxy-6-hydroxypyridine and the like.

In cases where the aromatic ring contained in the above φ¹ is apyrimidine ring, there may be mentioned, as examples of said compoundHφ¹X, 2-amino-4-fluoropyrimidine, 2-amino-6-fluoropyrimidine,4-amino-2-fluoropyrimidine, 4-amino-6-nitropyrimidine,2-amino-6-nitropyrimidine, 2-amino-4-hydroxypyrimidine,2-amino-6-hydroxypyrimidine, 4-amino-6-hydroxypyrimidine,2-amino-4,6-difluoropyrimidine,2-amino-4,6-dinitropyrimidine,2-amino-4,6-dihydroxypyrimidine, 4-amino-2,6-difluoropyrimidine,4-amino-2,6-dinitropyrimidine, 4-amino-2,6-dihydroxypyrimidine2-carboxy-4-fluoropyrimidine, 2-carboxy-6-fluoropyrimidine,4-carboxy-2-fluoropyrimidine, 4-carboxy-6-nitropyrimidine,2-carboxy-6-nitropyrimidine, 2-carboxy-4-hydroxyprimidine, 2-carboxy-6hydroxypyrimidine, 4-carboxy-6-hydroxypyrimidine and the like.

In cases where the aromatic ring contained in the above φ¹ is a triazinering, there may be mentioned, as examples of said compound Hφ¹X,2-amino-4,6-difluoro-1,3,5-triazine,2-amino-4,6-dichloro-1,3,5-triazine, 2-amino-4,6-dinitro-1,3,5-triazine,2-amino-4,6-dihydroxy-1,3,5-triazine,2-carboxy-4,6-difluoro-1,3,5-triazine,2-carboxy-4,6-dichloro-1,3,5-triazine,2-carboxy-4,6-dinitro-1,3,5-triazine,2-carboxy-4,6-dihydroxy-1,3,5-triazine, 3-amino-5-fluoro-1,2,4-triazine,3-amino-5-bromo-1,2,4-triazine, 3-amino-5-chloro-1,2,4-triazine,3-amino-5-nitro-1,2,4-triazine, 3-amino-5-hydroxy-1,2,4-triazine,3-carboxy-5-fluoro-1,2,4-triazine, 3-carboxy-5-bromo-1,2,4-triazine,3-carboxy-5-chloro-1,2,4-triazine, 3-carboxy-5-nitro-1,2,4-triazine,3-carboxy-5-hydroxy-1,2,4-triazine and the like.

Referring to the above-mentioned group —NR¹φ¹H, from the ligandstructure viewpoint, those ligands in which the functional group boundto the aromatic ring is bound to the meta position thereof show higherselectivity for LDL than those ligands in which the functional group isbound to the ortho or para position.

The “meta position” in this specification means the meta position forthe aromatic ring of the corresponding —NR¹φ¹H in regard to said —NR¹φ¹Xgroup occurring in the adsorbent of the present invention (thus, in thecase of a benzene ring, position 3 or position 5).

The above-mentioned X may be bound to either one of the meta positionsof said aromatic ring or both meta positions simultaneously. Further, inthe case of the above-mentioned X bound to both meta positionssimultaneously, the kind of the above-mentioned X may be the same ordifferent.

Said X is not particularly restricted but includes, for example, nitro,hydroxy, fluoro, bromo, chloro, iodo, methyl, ethyl, methoxy, ethoxy,thiol, cyano, amino, acetyl, hydrazyl, carboxy, isocyanato,isothiocyanato, aldehyde group and the like. In cases where said X canhave another substituent, said X may have a further substituent. Amongthe substituents specifically mentioned above, halogens, and hydroxy,nitro, acetyl, thiol and aldehyde groups are preferred.

The —NR¹φ¹X group has been described above. More specifically, asHNR¹φ¹X corresponding to the compound having the above-mentioned group—NR¹φ¹X, there can be mentioned 3-5-difluoroaniline,m-hydroxybenzylamine, m-nitrobenzylamine, m-fluorobenzylamine,m-hydroxybenzhydrazide, m-nitrobenzhydrazide, m-fluorobenzhydrazide,m-hydroxythiobenzamide, m-nitrothiobenzamide, m-fluorothiobenzamide,m-hydroxybenzenesulfonamide, m-nitrobenzenesulfonamide,m-fluorobenzenesulfonamide, m-hydroxyaniline, m-nitroaniline,m-fluoraniline, m-mercaptoaniline, m-methoxyaniline, m-aminophenol,m-aminoacetophenone, m-aminoindazole, m-aminobenzyl alcohol,m-hydroxybenzoic acid, m-nitrobenzoic acid, m-fluorobenzoic acid and thelike. Among them, 3,5-difluoroaniline, m-aminophenol,m-aminoacetophenone, m-nitroaniline and m-hydroxybenzoic acid arepreferred. These may be used singly or two or more of them may be usedin combination.

When the lipoprotein adsorbent of the present invention has theabove-mentioned group —NR¹φ¹X, selectivity for that is improved, namelythe lipoprotein adsorbent has at least about 1.5 times and at most about7 times higher selectivity when compared, in terms of the selectivityindex defined by the above formula (2), with the lipoprotein adsorbentsdisclosed in Japanese Kokai Publication Sho-63-208764.

The aromatic group of the φ¹ mentioned above is bound to the nitrogenatom of the group —NR¹φ¹X directly or via an atom. In cases where it isbound via an atom, such an atom or atomic group may be a carbon,nitrogen, oxygen, sulfur or phosphorus atom or the like. The nitrogenatom in the above group —NR¹φ¹X is associated with the selectivitydifference between LDL and HDL. According to the method of introducingthe —NR¹φ¹X group into the water-insoluble carrier, the nitrogen atom insaid group —NR¹φ¹X may be one originating from the water-insolublecarrier or one originating from the ligand. For example,

(1) when said —NR¹φ¹X group is a group derived from a compoundrepresented by the general formula

 (in which R¹, φ¹ and X are as defined above) (hereinafter alsoexpressed as “HNR^(1φ) ¹X”) and is immobilized on the water-insolublecarrier via the nitrogen atom of the above-mentioned compound, thenitrogen atom in said —NR¹φ¹X group is of ligand origin and

(2) when said —NR¹φ¹X group is a group introduced into a water-insolublecarrier by reacting the water-insoluble carrier having a grouprepresented by the general formula

 (in which R¹ is as defined above) (hereinafter also expressed as“—NR¹H”) with a compound represented by the general formula Zφ¹X (inwhich X and φ¹ and X are as defined above and Z represents a functionalgroup capable of reacting with an amino group or a part of saidfunctional group) the nitrogen atom in said —NR¹φ¹X group is of thewater-insoluble carrier origin.

Preferred as the compound represented by the above formula HNR¹φ¹X arecompounds in which X is a group selected from the group consisting ofhalogens and hydroxy, nitro, acetyl, thiol and aldehyde groups, andmixtures thereof. The compound represented by the above formula HNR¹φ¹Xmay be an aniline derivative or a mixture of aniline derivatives, abenzylamine derivative or a mixture of benzylamine derivatives, or thelike. These are readily available, hence are particularly useful. Theabove-mentioned aniline derivative is not particularly restricted butincludes, for example, aromatic alkyl-substituted anilines such asm-toluidine and 3,5-xylidine; aromatic alkoxy-substituted anilines suchas m-aminoanisole and 3-aminophenetole; anilines having one or moresubstituents of one or more kinds on the aromatic ring thereof, such asm-chloroaniline, m-bromoaniline, m-fluoroaniline, m-nitroaniline,3,5-dinitroaniline, 3,5-dichloroaniline, 3,5-dibromoaniline,3,5-difluoroaniline, m-aminobenzoic acid, ethyl m-aminobenzoate,3-aminoacetophenone, m-aminophenol, m-aminothiophenol, m-aminophenethylalcohol, m-aminobenzyl alcohol and m-phenylenediamine; and the like.Among them, 3,5-difluoroaniline, m-aminophenol, 3-aminoacetophenone andm-nitroaniline are preferred. These may be used singly or two or more ofthem may be used in combination.

Said benzylamine derivative is not particularly restricted but includes,for example, meta-fluorobenzylamine, 3,5-difluorobenzylamine,meta-bromobenzylamine, 3,5-dibromobenzylamine, meta-iodobenzylamine,3,5-diiodobenzylamine, meta-chlorobenzylamine, 3,5-dichlorobenzylamine,meta-nitrobenzylamine, 3,5-dinitrobenzylamine, meta-hydroxybenzylamine,3,5-dihydroxybenzylamine, meta-mercaptobenzylamine,3,5-dimercaptobenzylamine and the like.

The compound represented by the above formula Zφ¹X is not particularlyrestricted but includes, for example, m-hydroxybenzamide,m-nitrobenzaldehyde, m-methoxybenzaldehyde, m-fluorobenzaldehyde,3,5-dihydroxybenzaldehyde, 3,5-difluorobenzaldehyde,m-mercaptobenzaldehyde, m-nitrobenzoic acid, m-hydroxybenzoic acid,3,5-dinitrobenzoic acid, m-bromobenzoic acid, m-chlorobenzoic acid,m-fluorobenzoic acid, m-mercaptobenzoic acid, 3,5-dihydroxybenzoic acid,m-aminobenzoic acid and the like. Among them, m-hydroxybenzoic acid ispreferred. These may be used singly or two or more of them may be usedin combination.

In the above formula —NR²COφ²Y, R² represents a hydrogen atom or amethyl or ethyl group. CO represents a carbonyl group. φ² represents anatomic group comprising an aromatic ring bound to the nitrogen atom viasaid carbonyl group. COφ²Y represents an atomic group such that thecorresponding compound represented by Yφ²COH has a logarithmic valuelogP of 0 to 3.2, P being the partition coefficient in the water-octanolsystem, (to the exclusion of p-nitrobenzoic acid).

If the logP value of the compound represented by the above HOCφ²Y isless than 0, the hydrophobic interaction with lipoproteins will be weak,hence the lipoprotein adsorbing ability will be low. If said logP valueexceeds 3.2, not only LDL and VLDL but also HDL and other proteins willbe adsorbed simultaneously, raising a problem from the selectivityviewpoint. The above range is thus critical. It is preferred that saidlogP value be 0.8 to 2.7.

While it is stated in Japanese Kokai Publication Sho-63-208764 that thehydrophobicity of the aromatic ring-containing atomic group R^(b) in thegroup represented by the above general formula —NR^(a)R^(b) plays animportant role in the adsorption of lipoproteins, it has now newly beenfound that, from the ligand structure viewpoint, when said group R^(b)is bound via a CO bond, namely it is the above-mentioned —NR²COφ²Y, theselectivity for LDL is higher as compared with the cases where it isbound via a CS bond or CH₂ bond and that when the ligand has a specificfunctional group Y, said selectivity is still higher.

Although the above-mentioned logP value is influenced by the particularfunctional group (e.g. methylene group, carbonyl group or the like)directly bound to the aromatic ring, said value will not vary muchaccording to the presence or absence of such functional group or thekind thereof.

As the functional group Y, there may be mentioned, for example, halogensand hydroxy, acetyl, thiol, aldehyde, amino and like groups. Thearomatic ring contained in the above group φ² is not particularlyrestricted but may be any of the groups mentioned hereinabove inconnection with the above φ¹.

As the above group —NR²COφ²Y, there may be mentioned, in terms of thecorresponding compound HNR²COφ²Y, such compounds as m-bromobenzamide,o-bromobenzamide, p-bromobenzamide, m-chlorobenzamide,o-chlorobenzamide, p-chlorobenzamide, m-fluorobenzamide,p-fluorobenzamide, o-iodobenzamide, p-iodobenzamide, m-nitrobenzamide,o-nitrobenzamide, p-nitrobenzamide, m-mercaptobenzamide,o-mercaptobenzamide, p-mercaptobenzamide, m-hydroxybenzamide,o-hydroxybenzamide, p-hydroxybenzamide, 2,4-dihydroxybenzamide,2,5-dihydroxybenzamide, 2,6-dihydroxybenzamide, 3,5-dihydroxybenzamide,3,4,5-trihydroxybenzamide, m-aminobenzamide, o-aminobenzamide,p-aminobenzamide and the like. Among these, those having hydoxy, nitroor fluoro as the functional group Y, namely m-hydroxybenzamide,3,5-dihydroxybenzamide, m-nitrobenzamide, 3,5-dinitrobenzamide,m-fluorobenzamide, 3,5-difluorobenzamide and the like are preferred, andm-hydroxybenzamide, 3,5-dihydroxybenzamide, m-fluorobenzamide and3,5-difluorobenzamide are more preferred. These may be used singly ortwo or more of them may be used in combination.

When the lipoprotein adsorbent of the present invention has theabove-mentioned group —NR²COφ²Y, said adsorbent shows improvedselectivity, namely the selectivity index thereof as represented by theformula (2) mentioned above is at least about 2.5 times higher ascompared with the lipoprotein adsorbents described in Japanese KokaiPublication Sho-63-208764.

The nitrogen atom in the above group —NR²COφ²Y may be either ofwater-insoluble carrier origin or of ligand origin according to themethod of introducing the above group —NR²CO φ²Y into thewater-insoluble carrier. For example,

(1) when said —NR²COφ²Y group is a group derived from a compoundrepresented by the general formula

 (in which R², CO, φ² and Y are as defined above) (hereinafter expressedalso as “—HNR²COφ²Y”) and immobilized on the water-insoluble carrier viathe nitrogen atom in the compound mentioned above, the nitrogen atom inthe above —NR²COφ²Y group is of ligand origin.

(2) When said —NR²COφ²Y group is introduced into a water-insolublecarrier by reacting the water-insoluble carrier having a grouprepresented by the general formula

 (in which R² is as defined above) (hereinafter also expressed as“—NR²H”) with a compound represented by the general formula Yφ²COOH (inwhich Y and φ² are as defined above), the nitrogen atom in said—NR²COφ²Y group is of water-insoluble carrier origin.

As the compound represented by the formula HNR²COφ²Y, there may bementioned those specifically given hereinabove.

The compound represented by γφ²COOH is not particularly restricted butincludes, for example, those compounds in which one or more groups eachselected from the group consisting of halogens, hydroxy, acetyl, thiol,aldehyde and amino are bound to the aromatic ring of φ². As specificexamples, there may be mentioned m-bromobenzoic acid, o-bromobenzoicacid, p-bromobenzoic acid, m-chlorobenzoic acid, o-chlorobenzoic acid,p-chlorobenzoic acid, m-fluorobenzoic acid, p-fluorobenzoic acid,o-iodobenzoic acid, p-iodobenzoic acid, m-mercaptobenzoic acid,p-mercaptobenzoic acid, o-mercaptobenzoic acid, m-hydroxybenzoic acid,p-hydoxybenzoic acid, o-hydoxybenzoic acid, 2,4-dihydoxybenzoic acid,2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid,3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, acetylbenzoicacid, acetylaminobenzoic acid, formylbenzoic acid and the like. Amongthem, m-hydroxybenzoic acid and p-hydroxybenzoic acid are preferred.These may be used singly or two or more of them may be used incombination.

It suffices for at least one of the above-mentioned —NR¹φ¹X group and—NR²COφ²Y group to occur on at least one part of the surface of thewater-insoluble carrier according to the present invention, and two ormore —NR¹φ¹X and/or —NR²COφ²Y groups may occur thereon.

The water-insoluble carrier to be used in the practice of the presentinvention may be an inorganic carrier; an organic carrier such as acarrier comprising a synthetic polymer or a polysaccharide; or acomposite carrier comprising an organic carrier and an inorganiccarrier. Considering the environment for lipoproteins occurring in thebody fluid, a hydrophilic carrier is preferred and, further, theadsorption of substances other than the target substances, namely theso-called nonspecific adsorption should be as little as possible. Assuch carrier, there may be mentioned, for example, polysaccharides suchas crosslinked agarose, crosslinked dextran, crosslinked cellulose,crystalline cellulose, crosslinked chitin and crosslinked chitosan;synthetic polymers such as styrene-divinylbenzene, crosslinked polyvinylalcohol, crosslinked polyacrylates and crosslinked polyamides; inorganiccarriers such as glass beads and silica gel; organic-inorganic compositecarriers comprising inorganic carriers, e.g. glass beads, whose surfaceare coated with a polysaccharide or some other organic macromolecularcompound; organic—organic composite carriers comprising organiccarriers, comprising synthetic polymers, whose surface are coated with apolysaccharide; and the like.

Said water-insoluble carrier may have a functional group which can beused for an immobilization reaction. As such group, there may bementioned amino, carboxyl, hydroxy, thiol, aldehyde, halogen,acidanhydride, amide, ester, epoxy, silanol and like groups. As thewater-insoluble carrier having the above-mentioned —NR¹H group amongsuch functional groups, for instance, there may be mentioned, forexample, water-insoluble carriers comprising materials originally havingsaid —NR¹H group, such as chitosan and the like; and water-insolublecarriers provided with said —NR¹H group by introducing said group intooriginally amino-free water-insoluble carriers by activating the latterwith cyanogen bromide, epichlorohydrin, 1,4-butanediol diglycidyl etheror the like, followed by reaction with a compound represented by thegeneral formula H₂NR¹ (in which R¹ is as defined above).

Preferably, said water-insoluble carrier is rigid.

The term “rigid” in this specification means that when thewater-insoluble carrier is packed uniformly into a cylindrical columnand blood, serum or plasma or a dilution thereof or such liquid afterpretreatment such as blood corpuscle removal or serum protein removal ispassed through the column, said carrier has rigidness to such an extentthat consolidation due to carrier deformation or the like will neveroccur.

If, when a column is packed with the adsorbent of the present inventionand incorporated into an extracorporeal circulation circuit,consolidation of the adsorbent occurs during on-line therapeutictreatment, a sufficient rate of flow of body fluid will not be obtainedany longer, whereby the treatment period has to be prolonged or it mayeven become impossible to continue the treatment. To avoid theconsolidation of the adosorbent, it is preferred that the adsorbent havea sufficient mechanical strength, namely it be rigid.

The microstructure of the adsorbent of the present invention may beporous or nonporous. For obtaining a high LDL and VLDL adsorbingcapacity per unit volume, however, it is preferred that the specificsurface area be large, namely the adsorbent be porous, in particularwholly porous.

Said “porous” preferably means that the pore volume amounts to not lessthan 20% of the apparent volume of the water-insoluble carrier and thespecific surface area amounts to not less than 3m²/g. Those carrierswhich fail to meet these requirements are not suited for practical usebecause of their limited adsorption capacity.

When said water-insoluble carrier is porous, it preferably has anexclusion limit molecular weight of 1 million to 100 million as measuredusing spherical proteins. When said water-insoluble carrier is porous,its exclusion limit molecular weight of not less than 1 million is usedsince it is necessary for LDL and VLDL molecules having a molecularweight of not less than 1 million to readily penetrate into pores of thewater-insoluble carrier. If the exclusion limit molecular weight is lessthan 1 million, the adsorption capacity will be small, hence suchcarrier will be unsuited for practical use. If said exclusion limitmolecular weight exceeds 100 million, the adsorbent will become weak inmechanical strength or the solid content of the adsorbent will be toolow to have a sufficient adsorption capacity, hence will be unsuited forpractical use. Thus, a preferred range is 1 million to 100 million and amore preferred range is 3 million to 70 million.

Said exclusion limit molecular weight is the molecular weight of thesmallest molecule among molecules which are incapable of penetratinginto pores in gel permeation chromatography, namely are excluded, asdescribed, for example, in the monograph “Jikken Kosoku EkitaiKuromatogurafi (Experiments in High Performance Liquid Chromatogarphy)”(Hiroyuki Hatano and Toshihiko Hanai, published by Kagaku Dojin).

The porous carrier mentioned above is not particularly restricted butincludes, for example, porous cellulosic carriers, porous chitosancarriers, vinylic porous carriers comprising styrene-divinylbenzenecopolymers, crosslinked polyacrylates and crosslinked polyvinyl alcohol;and inorganic porous carriers such as glass, silica, alumina and thelike.

As the method of producing the lipoprotein adsorbent of the presentinvention, there may be mentioned, for example, the method forintroducing the above group —NR¹φ¹X by the method which comprisesbinding a compound represented by the above formula HNR¹φ¹X to awater-insoluble carrier via the nitrogen atom in said compound orreacting a water-insoluble carrier having the above-mentioned group—NR¹H with a compound represented by the above Zφ¹X, for instance, ormethod for introducing the above group —NR²COφ²Y by the method whichcomprises binding said compound represented by the formula HNR2COφ²Y toa water-insoluble carrier via the nitrogen atom in said compound orreacting water-insoluble carrier having the above-mentioned grouprepresented by —NR²H with a compound represented by the above formulaYφ²COOH for instance. Further, there can be used the method whichcomprises introducing the above-mentioned group —NR¹φ¹X or —NR²COφ²Yinto a water-soluble macromolecular compound and then subjecting thereaction product to crosslinking or like treatment to thereby obtain anadsorbent in the form of a water-insoluble form.

Said water-soluble macromolecular compound is not particularlyrestricted but includes, among others, polysaccharides such as dextranand starch; polymers such as polyvinyl alcohol and saponificationproducts derived from ethylene-vinyl acetate copolymers with a lowethylene content; and the like.

The adsorbent obtained by the above production method has theabove-mentioned —NR¹φ¹X or —NR²COφ²Y group introduced into theabove-mentioned water-insoluble carrier or the above-mentionedwater-soluble macromolecular compound. The method of immobilization isnot particularly restricted but may be any of various known ones, suchas physical, ionic or covalent bonding.

In the practice of the present invention, however, it is preferred thatthe ligand is immobilized on said water-insoluble carrier orwater-soluble macromolecular compound in the manner of covalent bondingwhich affords little possibility of ligand leakage. Moreover, ifnecessary, a spacer may be introduced between the water-insolublecarrier and the ligand, namely the group —NR¹φ¹X or —NR²COφ²Y.

The form or shape of the adsorbent of the present invention is notparticularly restricted but may be selected from such arbitrary shapesas granules, aggregates of particles, fibers, membranes and hollowfibers.

The adsorbent of the present invention can be used for removing LDL andVLDL from lipoprotein-containing liquids such as blood, serum or plasma,dilutions thereof, or liquids obtained therefrom after such pretreatmentas blood corpuscle removal or serum protein removal. More specifically,it can be used as an adsorbent for the treatment of patients withhyperlipidemia or as an adsorbent for the analysis of variouslipoproteins.

The adsorber of the present invention comprises an adsorption sectioncontaining the lipoprotein adsorbent of the present invention, a liquidinlet section for a liquid to flow into said adsorption section and aliquid discharge section for the liquid that has flown into saidadsorption section to flow out of said adsorption section. It ispreferred that said adsorber is provided with a filter which said liquidand components contained therein can pass through but the adsorbent ofthe present invention cannot pass through.

For using the adsorbent of the present invention for therapeuticpurposes, various techniques are available. The simplest and easiesttechnique comprises pooling blood of a patient extracorporeally in ablood bag or the like, admixing the blood with the adsorbent of thepresent invention to remove LDL and VLDL, removing the adsorbent bypassing through a filter and returning the blood to the patient. Whilethis technique does not require any complicated apparatus, the amount ofblood per one treatment is small. Moreover, it is time-consuming andtroublesome.

Another technique comprises using an adsorber packed with the adsorbentof the present invention.

Specifically, an adsorber comprising a column packed with the adsorbentof the present invention is incorporated in an extracorporealcirculation circuit, and the adsorption and removal are effected on linemode. As said treatment, there can be mentioned the method whichcomprises circulating plasma whole blood directly through said circuitor the method which comprises separating plasma from blood and passingthe plasma through said adsorber. The adsorbent of the present inventionand the adsorber in which said adsorbent is used can be used for bothmodes of treatment.

BEST MODES FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail. These examples, however, are by no means limitative of the scopeof the present invention.

REFERENCE EXAMPLE 1

Ten milliliters (10 ml; sediment volume) of a porous cellulosic carrier(product of Chisso Corp., exclusion limit molecular weight for sphericalproteins; 5.0×10⁷, mean grain size; 184±24 μm) was taken and washed withabout 1 liter of reverse osmosis water. After washing, the carrier wastransferred onto a glass filter and dried by 15 minutes of suction usinga suction pump. After thorough stirring, 0.131 g (corresponding to 0.2ml as adsorbent sediment volume) of the carrier was weighed and placedin a microtube (Nunc Co., Cryo Tube, capacity 1.8 ml), 1.5 ml of humanserum (product of Kokusai Bio Co.) was added, and the mixture was shakenat 37° C. for 2 hours. After shaking, the supernatant was assayed fortotal cholesterol (hereinafter, “TC”; using Cholesterol-HR (product ofWako Pure Chemical Industries)), triglycerides (hereinafter, “TG”; usingClinimate TG-2 reagent (product of Daiichi Pure Chemicals Co.)) andHDL-cholesterol (hereinafter, “HDL-C”; using HDL-C Auto “Daiichi”(product of Daiichi Pure Chemicals Co.)). The concentration ofLDL-cholesterol (hereinafter, “LDL-C”) was calculated from FriedewaldIsformula (Friedewald, W. T., et al., Clin. Chem. 18: 499, 1972) citedbelow. The concentration of HDL-C was 36 mg/dl and the LDL-C thereof was146 mg/dl.

(LDL-C)=TC−(HDL-C)−1/5TG  Formula (3)

EXAMPLE 1

Forty milliliters (40 ml; sediment volume) of the same porous cellulosiccarrier as used in Reference Example 1 (product of Chisso Corp.,exclusion limit molecular weight for spherical proteins; 5.0×10⁷, meangrain size; 184±24 μm) was taken, 40 ml of reverse osmosis water (ROwater, Yamato pure line RO 21; product of Yamato Kagaku Co.) was added,and the temperature was raised to 40° C. Thereto was added 12 ml of 20%NaOH, and the mixture was shaken at 40° C. for 30 minutes. Then, 12 mlof epichlorohydrin was added, and the mixture was shaken at 40° C. forfurther 2 hours to allow the reaction to proceed. After reaction, thecarrier was washed with about 2.5 liters of reverse osmosis water, togive an epoxidized carrier. The amount of the thus-introduced epoxygroup was 11.3 μmol/g.

To 30 ml of the thus-obtained epoxidized carrier was added a solution(24 ml) of 1 g of 3,5-difluoroaniline in aqueous ethanol and, whileallowing the mixture to stand at 50° C., the reaction was allowed toproceed for 6 hours. After reaction, the adsorbent was washed insequence with ethanol (about 1 liter) and reverse osmosis water (about 2liters), to give an adsorbent carrying 3,5-difluoroaniline immobilizedthereon. The thus-obtained adsorbent was treated in the same manner asin Reference Example 1, and the concentrations of HDL-C and LDL-C weredetermined in the same manner as in Reference Example 1. Then, thepercent adsorptions of different lipoproteins were calculated using theformulas (4) and (5) given below. The results are shown in Table 1. Theresult of calculation according to the formula (2) given hereinabove asan index of selectivity is also shown in Table 1.

Percent adsorption of HDL=[[(HDL-C concentration in ReferenceEx.)−(HDL-C concentration in Ex. or Comparative Ex.)]/(HDL-Cconcentration in Reference Example)]×100  (4)

Percent adsorption of LDL=[[(LDL-C concentration in ReferenceEx.)−(LDL-C concentration in Ex. or Comparative Ex.)]/(LDL-Cconcentration in Reference Ex.)]×100  (5)

EXAMPLE 2

An immobilized m-aminophenol-carrying adsorbent was obtained in the samemanner as in Example 1 except that 1.1 g of m-aminophenol was used inlieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtained was treatedin the same manner as in Reference Example 1, and the concentrations ofHDL-C and LDL-C were determined. The percent adsorptions of HDL and LDLwere calculated in the same manner as in Example 1, and the results areshown in Table 1. The result of calculation according to the aboveformula (2) as an index of selectivity is also shown in Table 1.

EXAMPLE 3

An immobilized m-aminoacetophenone-carrying adsorbent was obtained inthe same manner as in Example 1 except that 1.3 g of m-aminoacetophenonewas used in lieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtainedwas treated in the same manner as in Reference Example 1, and theconcentrations of HDL-C and LDL-C were determined. The percentadsorptions of HDL and LDL were calculated in the same manner as inExample 1, and the results are shown in Table 1. The result ofcalculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

EXAMPLE 4

An immobilized m-nitroaniline-carrying adsorbent was obtained in thesame manner as in Example 1 except that 1.3 g of m-nitroaniline was usedin lieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtained wastreated in the same manner as in Reference Example 1, and theconcentrations of HDL-C and LDL-C were determined. The percentadsorptions of HDL and LDL were calculated in the same manner as inExample 1, and the results are shown in Table 1. The result ofcalculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

EXAMPLE 5

To 30 ml of the epoxidized carrier obtained in the same manner as inExample 1 were added 30 ml of reverse osmosis water and 1.5 ml of 30weight % aqueous ammonia and, after thorough mixing, the mixture wasallowed to stand at 40° C. for 2 days to allow the reaction to proceed.After reaction, the carrier was collected by filtration and washed withwater to give an aminated carrier (hereinafter, “N-carrier”). Thethus-obtained N carrier (30 ml) was subjected to displacement washing ona glass filter with 150 ml of dioxane, 150 ml of 10% by volumetriethylamine in dioxane and 300 ml of dioxane in that order and thentransferred to a reaction vessel, and a solution of 890 mg ofm-hydroxybenzoic acid in 75 ml of dioxane was added. Thereto was added asolution of 300 mg of dicyclohexylcarbodiimide in 6 ml of dioxane, andthe reaction was carried out for 3 hours with stirring. Then, a solutionof 300 mg of dicyclohexylcarbodiimide in 6 ml of dioxane was furtheradded, and the reaction was carried out for 3 hours with stirring.Thereafter, the adsorbent was recovered by filtration and washed withdioxane, methanol, dioxane and water in the order mentioned to give anN-adsorbent carrying m-hydroxybenzoic acid as immobilized thereon. Theadsorbent obtained was treated in the same manner as in ReferenceExample 1, and the concentrations of HDL-C and LDL-C were determined.The percent adsorptions of HDL and LDL were calculated in the samemanner as in Example 1, and the results are shown in Table 1. The resultof calculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

COMPARATIVE EXAMPLE 1

An immobilized p-aminophenol-carrying adsorbent was obtained in the samemanner as in Example 1 except that 1.1 g of p-aminophenol was used inlieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtained was treatedin the same manner as in Reference Example 1, and the concentrations ofHDL-C and LDL-C were determined in the same manner as in ReferenceExample 1. The percent adsorptions of HDL and LDL were calculated in thesame manner as in Example 1, and the results are shown in Table 1. Theresult of calculation according to the formula (2) given hereinabove asan index of selectivity is also shown in Table 1.

COMPARATIVE EXAMPLE 2

An immobilized p-aminoacetophenone-carrying adsorbent was obtained inthe same manner as in Example 1 except that 1.3 g of p-aminoacetophenonewas used in lieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtainedwas treated in the same manner as in Reference Example 1, and theconcentrations of HDL-C and LDL-C were determined. The percentadsorptions of HDL and LDL were calculated in the same manner as inExample 1. The results are shown in Table 1. The result of calculationaccording to the above formula (2) as an index of selectivity is alsoshown in Table 1.

COMPARATIVE EXAMPLE 3

An immobilized p-nitroaniline-carrying adsorbent was obtained in thesame manner as in Example 1 except that 1.3 g of p-nitroaniline was usedin lieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtained wastreated in the same manner as in Reference Example 1, and theconcentrations of HDL-C and LDL-C were determined in the same manner asin Reference Example 1. The percent adsorptions of HDL and LDL werecalculated in the same manner as in Example 1, and the results are shownin Table 1. The result of calculation according to the above formula (2)as an index of selectivity is also shown in Table 1.

EXAMPLE 6

An immobilized p-hydroxybenzoic acid-carrying adsorbent was obtained inthe same manner as in Example 5 except that 890 mg of p-hydroxybenzoicacid was used in lieu of 890 mg of m-hydroxybenzoic acid. The adsorbentobtained was treated in the same manner as in Reference Example 1, andthe concentrations of HDL-C and LDL-C were determined. The percentadsorptions of HDL and LDL were calculated in the same manner as inExample 1, and the results are shown in Table 1. The result ofcalculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

EXAMPLE 7

An immobilized m-nitrobenzoic acid-carrying adsorbent was obtained inthe same manner as in Example 5 except that 1,0 g of m-nitrobenzoic acidwas used in lieu of 890 mg of m-hydroxybenzoic acid. The adsorbentobtained was treated in the same manner as in Reference Example 1, andthe concentrations of HDL-C and LDL-C were determined. The percentadsorptions of HDL and LDL were calculated in the same manner as inExample 1. The results are shown in Table 1. The result of calculationaccording to the above formula (2) as an index of selectivity is alsoshown in Table 1.

COMPARATIVE EXAMPLE 4

An immobilized benzylamine-carrying adsorbent was obtained in the samemanner as in Example 1 except that 1.0 g of benzylamine was used in lieuof 1.0 g of 3, 5-difluoroaniline. The adsorbent obtained was treated inthe same manner as in Reference Example 1, and the concentrations ofHDL-C and LDL-C were determined in the same manner as in ReferenceExample 1. The percent adsorptions of HDL and LDL were calculated in thesame manner as in Example 1, and the results are shown in Table 1. Theresult of calculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

COMPARATIVE EXAMPLE 5

An immobilized thiobenzamide-carrying adsorbent was obtained in the samemanner as in Example 1 except that 1.3 g of thiobenzamide was used inlieu of 1.0 g of 3,5-difluoroaniline. The adsorbent obtained was treatedin the same manner as in Reference Example 1, and the concentrations ofHDL-C and LDL-C were determined in the same manner as in ReferenceExample 1. The percent adsorptions of HDL and LDL were calculated in thesame manner as in Example 1, and the results are shown in Table 1. Theresult of calculation according to the above formula (2) as an index ofselectivity is also shown in Table 1.

TABLE 1 % Adsorp- % Adsorp- Index of tion of HDL tion of LDLselectivity* Example 1 11 42 0.26 Example 2 11 54 0.20 Example 3 5 330.15 Example 4 9 34 0.26 Example 5 1 27 0.05 Example 6 3 25 0.12 Example7 3 21 0.14 Compar. Ex. 1 12 15 0.80 Compar. Ex. 2 3 3 1.0  Compar. Ex.3 0 0 — Compar. Ex. 4 23 62 0.37 Compar. Ex. 5 12 11 1.1  *Index ofselectivity for lipoproteins (based on the result of calculationaccording to the formula (2))

From Table 1, it is seen that, as for the adsorption of lipoproteins,the lipoprotein adsorbent of the present invention is low in percentadsorption of HDL and high in percent adsorption of LDL, hence has highselectivity.

INDUSTRIAL APPLICABILITY

The lipoprotein adsorbent of the present invention, which has theconstitution mentioned hereinabove, can adsorb and remove LDL and VLDLselectively from blood constituents or the like.

What is claimed is:
 1. A lipoprotein absorbent which comprises awater-insoluble carrier having, on at least one part of the surface ofsaid carrier, at least one group other than p-nitrobenzoic acid selectedfrom the group consisting of groups represented by the general formula,

which is a group derived from a compound represented by the formula

which is selected from the group consisting of 3,5-difluoroaniline,m-hydroxybenzylamine, m-nitrobenzylamine, m-fluorobenzylamine,m-hydroxybenzhydrazide, m-nitrobenzhydrazide, m-fluorobenzhydrazide,m-hydroxythiobenzamide, m-nitrothiobenzamide, m-fluorothiobenzamide,m-hydroxybenzenesulfonamide, m-nitrobenzenesulfonamide, m-fluoroaniline,m-mercaptoaniline, m-methoxyaniline, m-aminoacetophenone,m-aminoindazole, m-aminobenzyl alcohol, and groups represented by thegeneral formula,

wherein R² represents a hydrogen atom or a methyl or ethyl group, COrepresents a carbonyl group, φ² represents a group consisting of atomscomprising an aromatic ring bound to the nitrogen atom via said carbonylgroup, Y represents a group consisting of atoms bound to said aromaticring, to the exclusion of the case where Hφ²Y is benzene, and COφ²Yrepresents a group consisting of atoms such that the correspondingcompound represented by Yφ²COH has a logP value, P being the partitioncoefficient in a water-octanol system, of 0 to 3.2.
 2. The lipoproteinadsorbent according to claim 1, wherein the group represented by thegeneral formula,

is immobilized on said water-insoluble carrier via the nitrogen atom insaid compound.
 3. The lipoprotein adsorbent according to claim 1,wherein the group represented by the general formula,

is a group introduced into said water-insoluble carrier by reacting awater-insoluble carrier having a group represented by the generalformula,

with a compound represented by the general formula Zφ¹X wherein Zrepresents a functional group capable of reacting with an amino group ora part of said functional group.
 4. The lipoprotein adsorbent accordingto claim 1, wherein the compound represented by the general formula,

is at least one aniline derivative selected from the group consisting of3,5-difluoroaniline, m-fluoroaniline, m-mercaptoaniline,m-methoxyaniline, m-aminoacetophenone and m-aminobenzyl alcohol.
 5. Thelipoprotein adsorbent according to claim 1, wherein the compoundrepresented by the general formula,

is at least one benzylamine derivative selected from the groupconsisting of m-hydroxybenzylamine, m-nitrobenzylamine andm-fluorobenzylamine.
 6. The lipoprotein adsorbent according to claim 3,wherein the compound represented by the general formula Zφ¹X is at leastone benzoic acid derivative selected from the group consisting ofm-hydroxybenzamide, m-nitrobenzaldehyde, m-methoxybenzaldehyde,m-fluoro-benzaldehyde, 3,5-difluorobenzaldehyde, m-mercaptobenzaldehyde,m-nitrobenzoic acid, m-hydroxybenzoic acid, m-fluorobenzoic acid andm-mercaptobenzoic acid.
 7. The lipoprotein adsorbent according to claim1, wherein the group represented by the general formula,

is a group derived from a compound represented by the general formula,

and is immobilized on a water-insoluble carrier via the nitrogen atom insaid compound.
 8. The lipoprotein adsorbent according to claim 1,wherein the group represented by the general formula,

is a group introduced into a water-insoluble carrier by reacting saidwater-insoluble carrier having a group represented by the generalformula,

with a compound represented by the general formula Yφ²COOH.
 9. Thelipoprotein adsorbent according to claim 8, wherein the compoundrepresented by the general formula, Yφ²COOH is a compound or a mixturethereof wherein Y is one or more groups selected from the groupconsisting of halogen atoms and hydroxy, acetyl, thiol, aldehyde andamino groups.
 10. The lipoprotein adsorbent according to claim 1,wherein the water-insoluble carrier is a hydrophilic carrier.
 11. Thelipoprotein adsorbent according to claim 1, wherein the water-insolublecarrier is rigid and porous.
 12. The lipoprotein adsorbent according toclaim 11, wherein the water-insoluble carrier has an exclusion limitmolecular weight, as determined by using spherical proteins, of 1million to 100 million.
 13. A lipoprotein adsorber which comprises anadsorption section containing the lipoprotein adsorbent according toclaim 1, a liquid inlet section for a liquid to flow into saidadsportion section and liquid discharge section for the liquid that hasflown into said adsportion section to flow out of said adsportionsection.
 14. The lipoprotein adsorbent according to claim 2 wherein thewater-insoluble carrier is a hydrophilic carrier.
 15. The lipoproteinadsorbent according to claim 3, wherein the water-insoluble carrier is ahydrophilic carrier.
 16. The lipoprotein adsorbent according to claim 4,wherein the water-insoluble carrier is a hydrophilic carrier.
 17. Thelipoprotein adsorbent according to claim 5, wherein the water-insolublecarrier is a hydrophilic carrier.
 18. The lipoprotein adsorbentaccording to claim 6, wherein the water-insoluble carrier is ahydrophilic carrier.